His expulsion from the upper house would signal the end of his career in parliament, but he will still be able to wield immense political influence, relying on his wealth, his sway over the Italian media and the loyalty of millions of diehard supporters.

For any other leader in any other country, being ignominiously booted out of parliament as a result of a conviction for tax fraud would surely signal the end of their career.

But the 77-year-old billionaire has shown time and time again that he is able to overcome such obstacles and sustain the support of millions of Italians who admire his chutzpah, his personal fortune and his populist appeal.

"After the vote, he will be out of parliament, but he won't be out of politics," Roberto D'Alimonte, a politics professor at Rome's LUISS university, told The Telegraph.

"He still controls six or seven million votes – he has a hardcore constituency and they have not left him yet. As long as he holds onto those votes, you can't say it's the end for him politically, although it may be another step into the twilight zone. But this is a man who has resources – money, control over the media."

Dr Geoff Andrews, an expert on Italian politics at the Open University and the author of Not a Normal Country: Italy After Berlusconi, said: "The vote to remove him from parliament is unlikely to end his political career or his aspirations for power.

"After all that has happened – the fraud trials, the bunga bunga parties, and the mounting economic crisis – the centre-Right still leads in the polls and has no capable alternative leader.

"Berlusconi can be a tough opponent, and as a wounded jackal can be at his most dangerous."

Mr Berlusconi pulled his centre-Right Forza Italia (Go Italy) party out of the coalition government on Tuesday night, ostensibly in opposition to the 2014 budget.

So after seven months of giving his reluctant support to the coalition led by Enrico Letta, the centre-Left prime minister, he is now in opposition, from where he will be able to snipe at the government.

The law under which he is likely to be stripped of his seat in the Senate decrees that he be banned from holding office for six years.

But Mr Berlusconi's lawyers are determined to challenge the law, which was introduced in December 2012, arguing that it should not be applied retrospectively to his fraud case, which dates back years.

Even if he is not allowed to become a senator or MP again, much less prime minister, he will remain a key player.

"The vote to expel him will not stop Silvio Berlusconi from being the political leader of millions of Italians who still place their hopes in a free and liberal country," Il Giornale, a Right-wing newspaper owned by Mr Berlusconi's family, said in a front-page editorial today.

Mr Berlusconi himself said on Tuesday: "Italians who put their faith in me still see me as the leader of the centre-Right."

Once again he presented himself as a political martyr, claiming that he had been persecuted by a biased, Left-wing magistracy. "I have suffered a degree of judicial persecution that no other citizen of a Western democracy has ever experienced."

He has called for thousands of his supporters to protest outside Palazzo Grazioli, his mansion in central Rome, in the lead-up to the vote this evening.

He said the demonstration would be "legitimate and peaceful" but also warned: "It is just the start." His exclusion from parliament will strip him of a degree of immunity from prosecution and will leave him vulnerable to a number of ongoing court cases involving allegations of corruption, bribery, abuse of office and procuring prostitutes.

"Losing his immunity is what really concerns him," said Prof D'Alimonte. "He could even be arrested and sent to jail."

Prosecutors in Milan, Naples and Bari are pursuing cases against Mr Berlusconi, in scandals which range from the recruiting of call-girls for his "bunga bunga" parties to paying for sex with an under age prostitute and bribing an opposition politician.

"I'm told there is a race between the prosecutors to see who can get me first," he told MPs from his party, according to La Repubblica newspaper.

But he remained defiant. "It's not over yet – I will return to Palazzo Chigi (the office of the prime minister in Rome) in 2015," he reportedly said.